This present application relates generally to methods, systems, and/or apparatus for improving the efficiency and/or operation of turbine engines, which, as used herein and unless specifically stated otherwise, is meant to include all types of turbine or rotary engines, including gas turbine engines, aircraft engines, steam turbine engines, and others. More specifically, but not by way of limitation, the present application relates to methods, systems, and/or apparatus pertaining to improved inducer design for turbine engines.
Gas turbine engines typically include cooling systems that provide cooling air to turbine rotor components, such as turbine blades, in order to limit the temperatures experienced by such components. Prior art cooling systems usually acquire the air used to cool turbine components from the engine's compressor, after which it is diverted and subsequently directed to the turbine section of the engine through an axial passageway. A device commonly known as a radial-axial inducer is generally located at the exit end of such an axial passageway. In general terms, an inducer is a device used to accelerate and direct a flow of air in a gas turbine engine. Primarily, inducers are used to re-direct the axial flow of air bled from the compressor such that the flow is tangential to and in the same direction of the rotating rotor, which is why these component are often referred to as radial-axial inducers. Re-directing the flow of air in this manner allows it to more efficiently pass through rotating holes in the rotating rotor. In this way, the cooling air may move downstream and supply, for example, the cooling channels formed in hollow airfoils. In addition, inducers reduce the pressure of the cooling air, which reduces the relative temperature of the flow. The reduction in temperature, of course, allows the flow of compressed air to more effectively cool downstream components.
Conventional inducers are often described as having a “trumpet” appearance, as they generally have a conical shape that narrows from a large circular opening at the upstream end. As one of ordinary skill in the art will appreciate, the conical shape narrows to a throat, which represents the narrowest cross-section of the inducer. From the throat, the inducer has an approximate cylindrical profile that extends to an outlet at the trailing edge. The outlet generally has a highly optimized geometry that is fine-tuned for efficient aerodynamic performance.
It is not uncommon for field conditions or other variables to require that the throat be machined, i.e., enlarged, so that better performance may be obtained. These adjustments, for example, may be required so that an adequate supply of cooling air is delivered downstream. However, conventional inducer design that includes a cylindrical region extending from the throat to the trailing edge, makes such improvements substantially impossible without distorting or causing damage to the optimized geometry of the trailing edge. As a result, there remains a need for an improved inducer design that allows for a cost-effective method of adjusting throat geometry.